Myers’ PSYCHOLOGY (6th Ed)

1. Myers’ PSYCHOLOGY (6th Ed) Chapter 5 Sensation Adapted from James A. McCubbin, PhD Clemson University

2. Sensation • Sensation • a process by which our sensory receptors and nervous system receive and represent stimulus energy • Perception • a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

3. Sensation • Our sensory and perceptual processes work together to help us sort out complex processes

4. What colors do you see?

7. Sensation • Bottom-Up Processing • analysis that begins with the sense receptors and works up to the brain’s integration of sensory information • Top-Down Processing • information processing guided by higher-level mental processes • as when we construct perceptions drawing on our experience and expectations

10. Sensation- Basic Principles • Psychophysics • study of the relationship between physical characteristics of stimuli and our psychological experience of them • Light- brightness • Sound- volume • Pressure- weight • Taste- sweetness

11. Sensation- Thresholds • Absolute Threshold • minimum stimulation needed to detect a particular stimulus 50% of the time • Difference Threshold • minimum difference between two stimuli required for detection 50% of the time • just noticeable difference (JND)

12. Sensation- Thresholds • Signal Detection Theory • predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) • assumes that there is no single absolute threshold • detection depends partly on person’s • experience • expectations • motivation • level of fatigue

13. 100 Percentage of correct detections 75 50 Subliminal stimuli 25 0 Low Absolute threshold Medium Intensity of stimulus Sensation- Thresholds • Subliminal • When stimuli are below one’s absolute threshold for conscious awareness

14. Sensation- Thresholds • Weber’s Law- to perceive as different, two stimuli must differ by a constant minimum percentage • light intensity- 8% • weight- 2% • tone frequency- 0.3% • Sensory adaptation- diminished sensitivity as a consequence of constant stimulation

15. Vision- Stabilized Images on the Retina

16. Vision • Transduction • conversion of one form of energy to another • in sensation, transforming of stimulus energies into neural impulses • Wavelength • the distance from the peak of one wave to the peak of the next

17. Vision • Hue • dimension of color determined by wavelength of light • Intensity • amount of energy in a wave determined by amplitude • brightness • loudness

18. The spectrum of electromagnetic energy

19. Great amplitude (bright colors, loud sounds) Short wavelength=high frequency (bluish colors, high-pitched sounds) Long wavelength=low frequency (reddish colors, low-pitched sounds) Small amplitude (dull colors, soft sounds) Vision- Physical Properties of Waves

20. Vision • Pupil- adjustable opening in the center of the eye • Iris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening • Lens- transparent structure behind pupil that changes shape to focus images on the retina

21. Vision

23. Vision • Accommodation- the process by which the eye’s lens changes shape to help focus near or far objects on the retina • Retina- the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual information

24. Vision • Acuity- the sharpness of vision • Nearsightedness- condition in which nearby objects are seen more clearly than distant objects because distant objects in front of retina • Farsightedness- condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind retina

25. Vision • Normal Nearsighted Farsighted Vision Vision Vision

26. Retina’s Reaction to Light- Receptors • Rods • peripheral retina • detect black, white and gray • twilight or low light • Cones • near center of retina • fine detail and color vision • daylight or well-lit conditions

27. Retina’s Reaction to Light • Optic nerve- nerve that carries neural impulses from the eye to the brain • Blind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there • Fovea- central point in the retina, around which the eye’s cones cluster

29. Receptors in the Human Eye Cones Rods Number 6 million 120 million Location in retina Center Periphery Sensitivity in dim light Low High Color sensitive? Yes No Vision- Receptors

30. Pathways from the Eyes to the Visual Cortex

31. Cell’s responses Stimulus Visual Information Processing • Feature Detectors • nerve cells in the brain that respond to specific features • shape • angle • movement

33. How the Brain Perceives

34. Illusory Contours

35. Visual Information Processing • Parallel Processing • simultaneous processing of several aspects of a problem simultaneously

37. Visual Information Processing • Trichromatic (three color) Theory • Young and Helmholtz • three different retinal color receptors • red • green • blue

38. Color-Deficient Vision • People who suffer red-green blindness have trouble perceiving the number within the design

39. Visual Information Processing Opponent-Process Theory- opposing retinal processes enable color vision “ON” “OFF” redgreen greenred blueyellow yellowblue black white white black

40. Opponent Process- Afterimage Effect

41. Visual Information Processing • Color Constancy • Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

42. Audition • Audition • the sense of hearing • Frequency • the number of complete wavelengths that pass a point in a given time • Pitch • a tone’s highness or lowness • depends on frequency

43. The Intensity of Some Common Sounds

45. Audition- The Ear • Middle Ear • chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window • Inner Ear • innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs • Cochlea • coiled, bony, fluid-filled tube in the inner ear that contains receptors for hearing

46. Audition • Place Theory • the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated • Frequency Theory • the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

47. How We Locate Sounds

48. Audition • Conduction Hearing Loss • hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea • Nerve Hearing Loss • hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve

49. Amplitude required for perception relative to 20-29 year-old group 1 time 10 times 100 times 1000 times 32 64 128 256 512 1024 2048 4096 8192 16384 Frequency of tone in waves per second Low Pitch High Audition • Older people tend to hear low frequencies well but suffer hearing loss for high frequencies

50. Touch • Skin Sensations • pressure • only skin sensation with identifiable receptors • warmth • cold • pain